1. Field of the Invention
The present invention relates to an air conditioning apparatus for a vehicle, having an inside/outside air switching function and a deodorizing filter function.
2. Description of the Related Art
Drivers of vehicles on the road often find themselves running behind a diesel-powered transport discharging fumes with an unpleasant smell. In such cases, it is customary for the vehicle's driver to shut off a flow of the diesel exhaust gas odor into the vehicle interior by setting the inside/outside air switching device of an air conditioning apparatus to a whole inside air mode, or by setting the same device to a whole outside air mode in which all outside air passes through a deodorizing filter to adsorb malodorous components from the outside air.
However, when the whole inside air mode is maintained for an extended period of time, a CO.sub.2 concentration of inside air in a passenger compartment is increased; and therefore, which can adversely affect physiological conditions of the driver and a passenger in the hermetically closed vehicle. Further, in the whole outside air mode, because the all outside air passes through the deodorizing filter, the air volume of the air conditioning apparatus is drastically reduced and the air conditioning capability is lowered correspondingly. Because a ventilation system of the air conditioning apparatus causes high pressure loss, noise of the ventilation system can be appreciably high.
Japanese Utility Model Laid-Open No. Hei 2-17413 proposes an air conditioning apparatus for a vehicle. In the conventional air conditioning apparatus, an arc-shaped circumferential wall of a rotary door is used to switch an inside/outside air intake port, and the rotary door incorporates a deodorizing filter. In the proposed air conditioning apparatus, inside and outside air passes continuously through the deodorizing filter regardless of a whole inside air mode or a whole outside air mode being selected. Therefore, the amount of air passing through the air conditioning apparatus is greatly decreased by the high pressure loss of the deodorizing filter.